Ex was down to hang, but then flaked?

Me and my ex (who broke up with me 8 months ago), made plans to meet up for drinks one weekend and she was totally down. I also followed up on the Friday to make sure, and again she was down to hang. When the day came, she texted me saying she won't be able to meet up because she was going to be busy with family things to do that day and appologized and said we should meet during the week. I replied normal and I said have a good time.

A few days later, I haven't heard back from her since. Is there a reason why she was so down to hang, and then flakes, and doesn't message me to reschedule, even though she said "we should meet up during the week"?

Updates:

Also, It doesn't SEEM that she has been with anyone since we broke up.

I should also ad that we've met up for coffee once before a couple months ago